export const snowShader = `
  uniform sampler2D colorTexture; //输入的场景渲染照片
  varying vec2 v_textureCoordinates;
  float snow(vec2 uv,float scale)
  {
    float time = czm_frameNumber / 60.0;
    float w=smoothstep(1.,0.,-uv.y*(scale/10.));if(w<.1)return 0.;
    uv+=time/scale;uv.y+=time*2./scale;uv.x+=sin(uv.y+time*.5)/scale;
    uv*=scale;vec2 s=floor(uv),f=fract(uv),p;float k=3.,d;
    p=.5+.35*sin(11.*fract(sin((s+p+scale)*mat2(7,3,6,5))*5.))-f;d=length(p);k=min(d,k);
    k=smoothstep(0.,k,sin(f.x+f.y)*0.01);
    return k*w;
  }
  void main(void){
    vec2 resolution = czm_viewport.zw;
    vec2 uv=(gl_FragCoord.xy*2.-resolution.xy)/min(resolution.x,resolution.y);
    vec3 finalColor=vec3(0);
    //float c=smoothstep(1.,0.3,clamp(uv.y*.3+.8,0.,.75));
    float c = 0.0;
    c+=snow(uv,30.)*.0;
    c+=snow(uv,20.)*.0;
    c+=snow(uv,15.)*.0;
    c+=snow(uv,10.);
    c+=snow(uv,8.);
    c+=snow(uv,6.);
    c+=snow(uv,5.);
    finalColor=(vec3(c)); //屏幕上雪的颜色
    gl_FragColor = mix(texture2D(colorTexture, v_textureCoordinates), vec4(finalColor,1), 0.5);  //将雪和三维场景融合
  }
`

export const rainShader = `
  uniform sampler2D colorTexture;//输入的场景渲染照片
  varying vec2 v_textureCoordinates;
  float hash(float x){
       return fract(sin(x*133.3)*13.13);
  }
  void main(void){
      float time = czm_frameNumber / 60.0;
      vec2 resolution = czm_viewport.zw;

      vec2 uv=(gl_FragCoord.xy*2.-resolution.xy)/min(resolution.x,resolution.y);
      vec3 c=vec3(.6,.7,.8);

      float a=-.4;
      float si=sin(a),co=cos(a);
      uv*=mat2(co,-si,si,co);
      uv*=length(uv+vec2(0,4.9))*.3+1.;

      float v=1.-sin(hash(floor(uv.x*100.))*2.);
      float b=clamp(abs(sin(20.*time*v+uv.y*(5./(2.+v))))-.95,0.,1.)*20.;
      c*=v*b; //屏幕上雨的颜色

      gl_FragColor = mix(texture2D(colorTexture, v_textureCoordinates), vec4(c,1), 0.5); //将雨和三维场景融合
  }
`

export const mosaicShader = `
  uniform sampler2D colorTexture;
  varying vec2 v_textureCoordinates;
  const int KERNEL_WIDTH=16;
  void main(void)
  {
      vec2 step = 1.0 / czm_viewport.zw;
      vec2 integralPos = v_textureCoordinates - mod(v_textureCoordinates, 8.0 * step);
      vec3 averageValue = vec3(0.0);
      for (int i = 0; i < KERNEL_WIDTH; i++)
      {
          for (int j = 0; j < KERNEL_WIDTH; j++)
          {
              averageValue += texture2D(colorTexture, integralPos + step * vec2(i, j)).rgb;
          }
      }
      averageValue /= float(KERNEL_WIDTH * KERNEL_WIDTH);
      gl_FragColor = vec4(averageValue, 1.0);
  }
`
